Hi,

Is this the correct positioning for the cooling flaps with a cold unexpanded bellows?

Somehow I think the rod may have been bent or the flaps twisted by the previous owner. I want to hook up the thermostat so I can have a wintertime heater.

Thanks...Dan

That is the hot position IIRC.

Thermostat cable connects with the connector in the down position...

So the flaps are both "up" or closed like this? As such, I will bring more cable through...correct?

Thanks...Dan

The system in question has ABSOLUTELY NOTHING to do with your having a heater this winter, or any other time.

The Cap'n

That wasn't my question Mr. Cap'n!

In the HOT position the diverter over the oil cooler closes down over the top of the cooler.. This directs air into and through the cooler only when the engine is at temperature.

If the diverter doesn't close completely over the cooler air will escape and oil temps will be elevated.

I check this function with a heat gun with the engine on the bench and the cooling tin off as it is critical.

I did a video of this when I built the most recent engine for my 912E, I might edit and share it sometime.

Oh? "I want to hook up the thermostat so I can have a wintertime heater."

The Cap'n

Thanks Jake...that makes sense. I'm good to go. I'll check it with a heat gun before I install the cylinder tins.

Dan

Looks like you have the heads on the wrong sides....Cht belongs on passenger side.....if your going to carbs...no problem....If FI, you might have to run a wire from harness to CHT...Just an observation

Look again...I believe the CHT is on the passenger side. The photo was taken from the flywheel (engine rear, front of car) side. BTW, this is going in a 912E.

Were the cable running to the thermo to break, would the flaps default to the full hot position? I'm in Texas and running hot and noticed that little arm doesn't ever move as far as it is in his picture above. (the hot position photo)

And we knew that because .... ?

ONLY attach the wire with the flaps in this position if you're sure the thermostat bellows are functioning. If your bellows have failed you will be setting up the motor for a MELTDOWN.

Yep, BTDT (in a former life...) Connecting the cable with the flaps in that position pretty much guarantees a meltdown, whether the bellows is working or not...

It's more important that the flaps OPEN fully than it is that they CLOSE fully!

The technique for setting the cable clamp is to remove the bellows mounting bolt so the bellows can follow the cable when you pull it up. (The bracket acts as the stop for it.)
The flaps need to be in the fully "open" or "hot" position when you tighten the cable clamp. (That's the position it is pulled to by the springs, so you don't need to move it if it is not binding.) Then pull the bellows back to it's mounting bolt and tighten the bolt. The cable will have pulled the flaps partly open.)

This way makes sure that the flaps are fully open when the bellows expands as much as the bracket will allow it to. They only close as much as the contracting bellows can pull them against the springs on the rod.

Ok for the position of the engine in the 912E- Yes ( passenger side ) , position for the CHT sender to operate with Fuel Injection- NO , the CHT needs to be over the Number 3 cylinder to capture the hotest cylinder -per Porsche / VW configuration.
We ( the forum members ) are trying to help with some advise . Good Luck , and do hope you get it running well.

Jack / Jaxdream

They aren't trying to bust your balls. They are trying to help you save an engine. Your CHT is on the #2 cylinder. It belongs on the #3 cylinder. We can clearly see it on the drivers side. Take the time to take it apart and reassemble the it the correct way now while its only a few hour job. Haste makes waste.

Jake was being subtle. write it on a calendar and take a picture.
your flap over teh cooler is tweeked in teh hot position and will not do its job . please fix it.

Good catch, Sean.

To clarify, there should be no gap when the bellows is _expanded_.

True, but it would be 'when the bellows are _expanded_.'

I don't know if newbs are allowed to audition for the grammar police, but "bellows" can be treated as a singular noun.

I don't like it. I decree my interpretation to be correct.

gramar police should has at least 200 posts to qualify. we need an admin ruling on this most impotant issue

phuch em , make hims dos a tyme aught &&&&&

Jack / Jaxdream

Just to be clear....I'm missing some parts from my system, so the flaps are in the default position which is the cold position??? Why not default the flaps to the hot engine condition and direct as much air as possible around the oil cooler?
Is that not more important than a quick warm up?
Am I inviting a meltdown? Temp. is around "half" on the gauge.
Or am I missing something?
Cheers

Mike, the default is to the hot in case the cable breaks.

I see three major points that have been made to the thread starter:

CHT is not on #3
Tin over oil cooler has gap
Proper setting/adjustment of cooling flaps

Those seem like engine life savers and the person who is building this engine should be thankful there are folks out here to point things like that out. Otherwise, it'd be a short lived engine.

Thanks guys...if I would have thought about that for one more minute, I wouldn't have posted!!!
Thanks,
Mike

Mike,

On the standard temp gauge in the console in the middle, the temp gauge should be under the T in TEMP pretty much ALL the time after warmup.

I have owned 6 914 4's and none of them ever went over the T on the Temp gauge, even in St. Louis, one of the hottest/most humid places on earth.

That motor is running VERY hot. Change the oil, check the sensor, and replace it just for safety's sake. Many on here say that 220 is warm for oil and 240 is BAD.

I believe them.

On a cold motor, flap bolt tiedown should be all the way to the REAR of the motor and the flap rod will rotate FORWARD at proper temperature.

CLOSED is default with wire attached firmly, and closed is the flaps rod pulled ALL THE WAY BACK, not forward. Maybe your rod is rotated so the flaps are in the wrong position on the rod? Not sure.

As the thermostat bellows heats, it expands and the wire lengthens, so to speak, and opens the flaps to divert heat to the oil cooler passenger side, and out the fan exit on the drivers side.

I had a wire break right after an engine rebuild and the main bearings scored and disintegrated because it ran too cold in NJ, on my first teener. Motor was toast in 1000 miles. Had to redo the bottom all over again. OUCH!

Too hot and many things can go even more badly.

Good luck!

John

I disagree with the "ALL the way" part.



Yes, closed is ALL the WAY back, but if you set it closed ALL the way, it will never get to open ALL the way. (The thermostat does not have enough range to do both.)

I maintain that when hot, it is more important to be completely open then it is to be completely closed when cold. YMMV in extreme cold environments of course. But summer? Make sure it's OPEN when warmed up.

I believe that the relevant rule is not "more than 200 posts", but "members with numbers less than 200".

That being so, I declare myself correct, and redeem the reputation of the newbie, who not only provided proof in his link, but an eloquent description of my correctness.

I have munificently corrected your spelling and grammar for your edification, Sir.

Everyone has an opinion based on experience on these 4 bangers, and I really do see what Mike is saying, but truly, the engine should not go over idle until it has come up to temp. Running cold is as dangerous as running hot. I will never forget the pieces in the strainer a week after reinstall and run in. WAS I PISSED OR WHAT?

My flaps on my current car, with a new bellows, wire and crimped end goes from all the way closed to mostly open in 5 minutes. It may not be totally open, and maybe a summer/winter variation is what is called for. If all the parts are good and correct, that is not at all unreasonable.

Does Jake or another builder have an opinion?

I actually measured it in each season over the last 2 years. Now SoCal is not even close tempwise to NorCal, or like someplace actually DAMN cold, but I blew an engine running too cold, and many have ruined engines too hot.

It is a 40 year old design.

John